This invention relates to a trim tab actuator for a marine propulsion device and more particularly to an improved operating arrangement for a trim tab that permits the operator to select any of a wide variety of trim tab functions for assisting in steering.
The use of trim tabs for marine propulsion devices so as to effect the steering of the watercraft are well known. For example, it has been proposed to mount a trim tab on a marine outboard drive and to pivot the trim tab in an opposite direction from the steering direction of the outboard drive so as to create a hydrodynamic force acting upon the outboard drive so as to assist in steering. Such devices normally operate by means including a form of lost motion connection in the steering mechanism. Although these devices are effective in assisting steering, these devices operate on a fixed ratio and hence do not always offer the appropriate degree of control. Furthermore, these devices, because of their fixed nature, only accomplish steering assist and hence do not enjoy the full benefits of the trim tab.
Other types of devices have been incorporated wherein the trim tab may be manually controlled by the operator in such a way that the operator can set the trim tab by a manual selection so as to achieve the desired trim tab function. However, these devices require an operator's continuous attention and hence are not completely satisfactory.
It has also been recently proposed to provide automatic actuators for operating the trim tab in response to sensed conditions of the watercraft and the steering input. For example, in the co-pending application entitled TRIM TAB ACTUATOR FOR MARINE PROPULSION DEVICE, Ser. No. 033,403, filed Apr. 1, 1987, in the names of Toshio Takeuchi and Shinya Atsumi, and assigned to the assignee of this application, there is disclosed an arrangement wherein a computer automatically controls the position of a trim tab so as to maintain a given course setting for the associated watercraft. Furthermore, in co-pending application entitled TRIM TAB ACTUATOR FOR MARINE PROPULSION DEVICE, Ser. No. 033,401, filed Apr. 1, 1987, in the name of Shinya Atsumi, and assigned to the assignee of this application, there is disclosed an arrangement wherein the trim tab can be actuated in such a way so as to provide steering sharpness as opposed to steering assist or directional control to avoid straying from the course set. These co-pending applications disclose other possible utilities for the trim tab. Furthermore, co-pending application entitled TRIM TAB ACTUATOR FOR MARINE PROPULSION DEVICE, Ser. No. 052,712, filed May 20, 1987, in the names of Toshio Takeuchi and Shinya Atsumi, and assigned to the assignee of this application, there is disclosed an arrangement wherein an operator may select one of a plurality of premapped conditions so as to permit the trim tab to be adjusted to achieve the desired steering result. Obviously, each of these three last mentioned co-pending applications indicate that the trim tab may be operated in a wide variety of functions so as to achieve a wide variety of purposes.
It is a purpose of this invention to provide an improved trim tab actuator which permits the operator to select not only the desired type of steering effect that will be accomplished by the trim tab, but also so as to select which of a wide variety of premapped conditions will be operative to control the trim tab position.
It is a further object of this invention to provide a trim tab actuator for a marine propulsion device in which the operator is given a wide variety of controls over both the effect and operation of the trim tab.